Sleep darts: The crossbow's primary usage. Bentley uses it to fire sleep darts from afar to put guards to sleep, allowing him to sneak by unnoticed or finish them off with a single bomb. He can also use his crossbow more tactically by firing the darts at explosive barrels, causing them to damage enemies in the vicinity. By using the binocucom, Bentley can zoom in his view to fire darts with better accuracy.
Melee: Should any enemies approach Bentley up close, he can fend them off by striking them with his crossbow. However, as it is not designed for intentional use as a melee weapon, the crossbow deals less damage than Sly's cane or Murray's fists. Due to its small size, it also has poor range. Despite this, Bentley can power up his crossbow to imbue it with the ability to shrink opponents whenever he hits them with the crossbow, giving him the opportunity to flee or knock them out with ease.
Early concept art of Bentley's main weapon prior to being changed to the crossbow used in the final version of the game.
In concept art of Bentley from Sly 2, instead of the crossbow that he would use in the final version of the game, he used a device held similarly to a firearm with a foregrip as his main weapon. Instead of a dart launcher, it is adorned with light bulbs and an antenna at the front end of the weapon. What this would have accomplished is unknown, though due to the shape of the device and the way Bentley held it, it could be presumed that it could fire projectiles at enemies. It is later replaced with the crossbow that he uses in the game.
However, the artwork used in Bentley's Gadget Grid shows him holding the device, implying that the weapon was replaced late in development.
The device's silhouette also appears (despite Bentley wielding the crossbow) in the short cutscene of the Cooper Gang gearing up whenever an episode is selected.
During the intro cutscene of Thieves in Time depicting a flashback with Octavio, Bentley can be seen wielding a "pistol" variation of the device.
The crossbow was only referred to by its name in the power-up description for Size Destabilizer. Murray referred to the crossbow as "dart gun" during the job "Sly/Bentley Conspire"; the crossbow was also called a dart gun in the Controls menu when playing as Bentley.
The crossbow is replaced with Bentley's wheelchair from Sly 3 onward, presumably due to the fact that he is not able to operate his wheelchair and hold the crossbow at the same time.
During the final cutscene of Sly 3 with Bentley writing in the Thievius Raccoonus, his crossbow can be seen lying on his desk.
In the introduction cutscene of Sly Cooper: Thieves in Time, Bentley can be seen equipping a crossbow, though its design differs from its appearance in Sly 2. However, like Sly 3, he is not physically seen using it as a weapon in-game.